Recently, as a data storage apparatus typically represented by a hard disk drive (HDD), a hybrid memory device which uses a nonvolatile memory such as a NAND flash memory (hereinafter simply referred to as a flash memory) together with a disk as storage media has been developed.
In such the hybrid storage apparatus, the flash memory comprises a storage area divided into a plurality of memory banks (hereinafter simply referred to as banks). A flash memory controller controls the flash memory in accordance with a so-called interleaving method which can simultaneously access to respective banks.
Here, an interface between the flash memory controller and the flash memory cannot transfer data simultaneously to the respective banks. Therefore, the flash memory controller has an arbitrator to arbitrate buses of the interface when a conflict occurs in access to a plurality of banks. By interleaving of the arbitrator, faster access is achieved.
However, in actual flash memory control, a series of processing including issuance of a read command needs to be performed for a read operation to read data from the flash memory. Therefore, simply performing arbitration with use of the interleaving method is not sufficient to reduce the time required for the read operation and to realize reading efficiency.